The flow of fluid through sandwich plate valves. The article concerns the analysis of pressure losses during flow through the unit of three valves: 4-way direct operated directional control valve, throttle valve and non-return valve, which are mounted in sandwich system on the subplate, according to the standard ISO 4401-05. The results of the analysis show that the pressure losses during flow through the valve unit are lower in comparison to the summary results of pressure losses during flow through the individual valves.

Poppet directional valves with surface coated for water hydraulics. Tests cover: time response determination, elaboration of flow characteristics for singular valves as well as design and manufacture of four way manifolds and functional investigations in hydrostatic drive of manipulator arm. It was found that the selected poppet shut-off valve with coated parts passed positive functional tests in experimental set-up for water environment. The coatings showed good adhesion to steel parts of the valve, thus this technique can be used to adjust the steel valves for use in water hydraulic systems.

Maintenance-guarantee for prolonging the lifespan of fluid power installations. The article presents selected issues regarding the activity of maintenance the required parameters of the hydraulic fluid in the hydraulic systems and components. It lists also the equipment required for performing tests of fluid in hydraulic systems and components, after their upgrade or repairs. It is also presented selected results of tests of hydrostatic axial piston pump after repair.
Correction of static flow characteristics. This paper presents a simplified way of minimizing the impact on deviation on the static speed-flow characteristics. Presented solutions relate to linear systems.

Influence of throttle control methods on noisiness of hydrostatic transmission. In the paper some reasons of noisiness of hydrostatic transmission during unstable state have been indicated. Control methods for noise reduction, especially throttle methods: serial and parallel have been described. A significant correlation between maximum pressure ripple during start-up of the hydrostatic gear and noise generated by the system has been presented.